Time-limit controller for circuit-breakers.



No. 794,981. PATENTED JULY 18, 1905. E. M. HEWLETT.

TIME LIMIT CNTROLLER EUR CIRCUIT BREAKERS.

APPLIOATION FILED JUNE 22, 1903.

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No. '794,981- PATBNTED JULY 18, 1905. E. M. HEWLETT.

TIME LIMIT CONTROLLER FOR CIRCUIT BREAKERS.

APPLICATION FILED JUNE 22, 1903.

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No. 794,981. I A PATBNTED JULY 18, 1905. E. M. HEWLETT.

TIME 'LIMIT CONTROLLER FOR CIRCUIT BREAKERS.`

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No. I794,981.

UNITED STATES Patented July 18, 1905.

PATENT OEEICE.

EDWARD M. HEWLETT, OF i SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

TIME-LIMIT CONTROLLER FOR CIRCUIT-BREAKERS.

SPECIFICATION forming part of Letters Patent No. I794,981, dated July 18, 1905.

l Application filed June 22,1903. Serial No. 162,496.

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Be it known that I, EDWARD M. HEWLETT, a citizen of the United States, residing at Schenectady, county of Schenectady, State of New York, have invented certain new and useful Improvements in Time Limit Controllers for Circuit-Breakers, of which the following is a specification.

In governing automatic switches or circuitbreakers it has been the practice for some years to distinguish between a moderatelyheavy overload, which the protected apparatus could carry for some time without damage, and an extreme overload, whichshould be removed instantaneously to insure the safety of the protected apparatus. This selective property of the switch or circuitbreaker is governed by a time-limit device which is affected by a lower overload and which is so constructed that if said overload persists for a definite interval the tripping of the circuit-breaker will ensue, but if it does not persist the parts will be restored to their normal condition without operating the circuit-breaker. The time-limit devices commonly employed are wheel-trains set in motion when an overload occurs. In modern systems of distribution, and particularly those adapted for lighting or power circuits, a considerable number of independent feeders extend lfrom the generating-station or some distributing-station supplied thereby. My invention is especially valuable for systems of this character where a plurality of feeders are to be protected by time-limit control devices.

One essential feature of my invention comprises a single timing device adapted to cooperate with any of a plurality of controllers, governing-switches, or breakers for different feeders or circuits. Thus the expense of equipping a station with control devices is reduced materially, since each timing device answers for all of the instruments instead of requiring as many timing devices as there are control instruments for the feeders. The timing device I employ is itself novel in construction, comprising a worm driven by a motor, which worm is adapted to engage any of thetrip-control devices when an overload exists on any circuit, or all of them if occasion requires, and start a movement along the worm of a circuit-closing arm, which after a definite predetermined range of movement closes the trip-circuit.

The invention embodies various more or less subordinate features of novelty, which will be hereinafter more fully described and will be definitely pointed out in the claims accompanying this specification.

In the accompanying drawings, which illustrate my invention, Figure 1 is a sectional view of a time-limit control device embodying my improvements. Fig. 2 is a top plan view of the several trip-control devices. Fig. 3 is a side elevation, on an enlarged scale, showing the relation of the motor-operated worm or screw to the trip-control device. Fig. 4 is a diagram showing the relation of the several trip-control devices to the switches or circuit-breakers with which they coperate, and Fig. 5 is asimilar view in connection with a polyphase alternating system. Fig. is a partial front elevation of a trip device.

Referring first to the instrument as depicted in Figs. 1, 2, and 3, 1 represents a casting formed as a hollow casing adapted to rest on the floor of the station and of sufficient height to permit instruments to be conveniently viewed from the glazed cover in the top. The cover is hinged' and provided with a latch, as indicated in Fig. 1 at 2, and may be provided with means for locking the cover to prevent interference with the mechanism. On brackets within the casing is mounted an insulating-platform 3, through the center of which extends a shaft on which is mounted a drum 4, the periphery of which is grooved helically with a worm. Motion is communicated to the drum by a worm-gear 5 and worm 6, driven by gearing connected with an electric motor 7. The worm-gearing is inclosed in a casing 8, which may be Hooded with oil by means of the supply-pipe 9. The

motor is supported in brackets 10 and 11, being held in position by clamps, as indicated By loosening the bolts which sein Fig. l,

cure these clamps the motor with its connected gear may be withdrawn through the door 12 in the side ol the hollow standard. The motor-circuit may be arranged so as to be permanently closed or may be closed at the time a relay operates responsive to an overload in one of the circuits. I prefer to maintain it in continuous operation, so that the drum 4 is continuously revolving. Arranged in circular' order around the drum 4 as a center is a group of trip-control devices each comprising a magnet 13 and armature 14, the several magnets being in local circuits controlled by relays responsive to overload conditions in the several protected circuits. The armature 1.4, governed by a retractile spring 14, is connected by a yielding elastic connection with a hinged bar 15, carrying a yielding circuit-closing contact 1,6. This is effected by slotting the end of the bar and mounting it on a pivot in theforked end of the armature, a helical spring 14h nesting behind the pivot. The extremity olE this bar has a groove edge adapted to mesh with the screw-thread on the drum 4, to the end that when the magnet 13 is energized the bar 15 will be thrust into active relation to the wormdrum, and the revolution of the latter will gradually feed the bar upwardly in the figure until the contact 16 engages a back-stop 1 7. This back-stop is mounted on the end of along screw, the contact-point being of silver or similar inoxidizable material. By adjusting the screw up or down the range of motion necessary before contact is completed will evidently be varied, and this constitutes a time-limit device on which the period of time may be varied and may be predetermined with great accuracy. The drum being driven by a shunt or other constant-speed motor at a uniform speed, the time-limit may be set with great accuracy. As will be evident from Fig. 2, these devices may be grouped within a small space radially around the drum, each bar being in operative relation to the worm on the periphery of the drum, ready instantly to be dropped into clutch. Itwill be evident, moreover, that the motion of anyone or me re is absolutely independent of the motion o'l the others, since all are carried by a motion of translation parallel to the axis and any one may be thrown into clutch or disconnected without interference with the others. Each trip-control instrument car-ries also an insulated spring-eontact 18, cooperating with another spring-contaet 19, mounted en the armature, these two being brought into engagem ent when the armature is operated and the clutch-bar 15 shifted into active relation to the worm-drum.

The circuit relations of the several instruments will be understood 'lrom examination of Fig. 4. 20, 2,1, and 22 represent a group of automatic switches governing the supply of energy from a group el bus-bars to feedercircuits 23, 24, and 25. ln series relation to the several feeders are coils 2G, operating with a movable core 27 and acting as a relay for the several trip-control. devices hereinbelore described.' When one of these relays carries a predetermined excess ol" current or a definite overload which would alter a short time endanger the salety of the installed apparatus, the core 27 is lifted, bridging two contacts and closing a circuit from the Afeeder to the magnet-coil 13 el the correspomling trip-control device through a resistance 2h. The magnet 1 3 is thereby energized and the bar 15 shifted into engagement with the worm-drum, the contacts 18 and 19 being simultaneously closed. The rotation el" the worm-drum gradually shifts the bar l5 upwardly, and if the overload continues lor a predetermined time limit will connect contacts 16 and 17, thereby closing the circuit through an auxiliary trip-coil 2) on the switch or cireuit-ln'eaker et the overloaded feeder. This circuit maybe traced l'rom the le'l't leg of the feeder through auxiliary tripcoil 29, wire 30, adjusting-screw 1,7, contact 16, contacts 19 and 18, wire 31, to the right leg of the feeder. Thus the auxiliary coil 2i) is energized and the circuit-breaker operated. If, however, the overload had disciimtinued before the full range of motion of the bar 15 had been effected, the core of the relay 26 would have dropped, thereby denergizing the magnet 13 and permitting the armature 14 to drop back under the influence of its control-spring 14, when the bar 15 would be withdrawn from engagement with the wormdrum and would 'fa l to its normal retracted position, as indicated in Fig. 1. The first movement of retraction on'the part of the armature opens the trip-coil circuit at the contacts 18 and 19. These contacts may be shed with carbon, so as to take the are without damage. The trip-coils shown in Fig. 4 are compound, one coil carrying the load el. the feeder and the other being an auxiliary coil governed bythe trip-control devices hereinbefore described. Il an overload immediatelydangereus to the apparatus occurs, then. the series coil 32 would set up a sufficient llux, unassisted bythe auxiliary coil, to trip the circuit-breaker. Under a time-limit overload, however, the insu'lliciency of this series coil is supplied by the energy furnished by the auxiliary trip-control device. The trip -control devices being grouped in this way about a common timing device permit a simple and cheap organization to govern all the circuits el the station and bring all olI the circuits in the station within the cognizance oi' an operator at a single point.

In Fig. 5 is shown anv arrangement ol circuits suitable for a polyphase system. The particular arrangement shown is adapted for use with high-tension currents, oil-switches 32 33, &c., being shown. These are illus- IOO IlO

trated'merely ina conventional way, being governed by a latch, as 34, controlled by a trip-coil the energization of which depends upon the trip-control device shown at 35, the construction of which is the same as that of the type hereinbefore described. rlhe closure of the trip-circuit is dependent upon the operation of a relay, as before, the controlcoil of the relay being supplied from the polyphasesystem. Each relay is shown as related inductively to several of the mains of the system. For example, in the drawings a triphase system has been depicted and two current-transformers 36 and 37 are connected in two of the phases. The secondaries of these transformers are cross-connected and leads are taken from these connections to the control-coil of the relay 26a. The particular arrangement of transformers shown is not of my invention and is shown merely by way of example. This is fully set forth and claimed in the application filed by C. E. Eveleth, Serial No. 175,579, filed on or about October 3, 1903. ln this system but a single trip-coil is used to govern the breaker for all phases of the circuit, the transformers in two of the three phases having a connection, as shown in the drawings, with a single trip-coil. The secondaries of the transformers are preferably cross-connected, so as to place the two phases in the three-phase system at an angle of sixty degrees, whereby the resultant current in the trip-coil would approximately be 1.8 times the current flowing in either of the secondary circuits. As a result of this connection the oil-switch is always tripped on overload of either of the three-phase lines.

Having thus described my invention, what l claim as new, and desire to secure byLetters Patent of the United States, is-

1. A time-limit circuit-controller comprising a movable device, a plurality of electrically-governed circuit-controllers adapted to be connected therewith, each circuit-controller being responsive to predetermined change of load-in its circuit, and tripping devices for switches or circuit-breakers in the several controlled circuits governed by said circuit-controllers.

2. The combination of a plurality of electroresponsive devices governing different line-wires, circuit-breakers controlled thereby, and a trip device common to all of the circuit-breakers governed by any electroresponsive device to trip the breakers separately or collectively.

3. The combination of a plurality of elec- -troresponsive devices governing different line-wires, circuit-breakers controlled thereby, and a time-limit trip device common to all of the circuit-breakers governed by any electroresponsive device. L

4. The combination of a plurality of electroresponsive devices governing different line-wires, each device provided with a clutch, a trip device common to all of the devices in operative relation to the clutch, and circuit-breakers for the several line-wires governed by the trip device to open the breakers separately or collectively. y

5. The combination of a plurality of electroresponsive devices governing different line-wires, a movable trip-contact for each, a motor device, means for connecting the same mechanically with the several contacts, means for producing a slow movement of the contacts when so connected, and circuitbreakers in the several line-wires tripped when the respective contacts complete a predetermined range of motion.

6. The combination of a plurality of electroresponsive devices governing different line-wires and responsive to energy flowing therein, a rotatory device, a trip device controlled by each electroresponsive device having a determinate range of movement before tripping, circuit-breakers tripped by the several trip devices, and means 'or clutching the several trip devices to the rotatory device when their operating devices are actuated.

7. A time-limit device comprising a current-relay, a rotatory drum carrying a worm, a movable circuit-controller controlled by the relay and adapted to engage the worm, and a trip-circuit controlled by the circuitcontroller after a predetermined range of motion.

8. A time-limit device comprising an electroresponsive device sensitive to energy in a protected circuit, a motor-operated worm, a circuit-controller operated by the electroresponsive device and adapted to be clutched to theworm, and a trip-circuit actuated after a Vpredetermined range of movement. 9. A trip device for a circuit-breaker comprising a magnet, an armature, a retractile arm, a rotatory worm, means for shifting the arm into and out of clutch with the worm by the magnet, and means for tripping a circuitbreaker after a predetermined movement of the arm.

10. A trip device for a circuit-breaker comprising a magnet, an armature, a retractile arm, a movable element, means for shifting the arm into and out of engagement with the movable element by the magnet, a trip-contact on the arm, a trip-circuit controlled by a predetermined movement of the arm, and a secondary arcing-contact to open the. tripcircuit at a point distinct from the trip-contact.

11. A multiple time-limit circuit-controller comprising a plurality of magnets responsive to electrical conditions in different lines, a movable arm for each, and a rotatory worm adapted to feed each arm progressively when its control-magnet is actuated.

12. A multiple time-limit circuit-controller comprising a plurality of magnets responsive to electrical conditions in different lines,

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a movable arm Yfor each, and a rotatory Worm about which the arms are arranged in circulail order, said Worm being adapted to 'feed eacli arm progressively when its control-magnet is actuated.

13. A n'iultiple time-limit device eoniprising a plurality of tripping devices eaeli llavingr a control-magliet7 a common timing device, a casing inclosing tlie parts, and a reinovable motor -for operating the timingr de vice.

14. The combination of a hollow stand ardI 

